my graphics card wont work

i bought a new motherbord it's a gigabyte GA-G41M-ES2L it came with a built in graphics car but i already had my geforce 9400 gt card but when i star the pc it won't work monitor only disblay in the built in vga but when i reset the computer the geforce card works , a few days ago i replaced my powersupply and my geforce card wont work any more even when i reset my system i dont know what to do

i changed the power supply bec. it gave a strange noise from it's fan and it wasn't functioning any more and yes i connected every thing while installing the new one ,the new power supply is made in china and its model is creative ,and yes i have gone to the bios setup and made all what you said and with no result ,i even unplugged the geforce card from the motherboard and connected it again and it's fan is working so i guess it's properly connected

Please (this is important) supply the make and model number of the power Supply as well as ALL of the detailed specs INCLUDING Wattage, as well as (more important) the Amperage on all rails (5V, 3.3V, 12V (all if more than one)). I am suspecting that you purchased a cheap power supply that is faulty and/or underpowered and that is your entire problem.You should have purchased a quality name brand with a single 12Volt rail, active PFC, 80% or greater certified efficiency rating, 12Volt amperage significantly higher than either the 3.3V or the 5V rails, and a decent warranty (3 to 5 years).

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